package main

import (
	"flag"
	"fmt"
	"time"
)

var (
	period time.Duration
)
//标准库看一看
// net/http net/rpc runtime refeclt pprof
// cache
func init()  {
	flag.DurationVar(&period,"peroid",1*time.Second,"sleep period")
}
func main() {
	flag.Parse()
	fmt.Printf("Sleeping for %v...",period)
	time.Sleep(period)
	fmt.Println()
}
